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Enlargement History: North Sterling Reservoir has never been enlarged. <br />Reservoir Storage Measurement: Storage levels in North Sterling Reservoir are measured <br />using a stilling well within the embankment. Because the stilling well is connected to the <br />reservoir outlet pipes, measurement is only possible when water is not being released. <br />Older measurements were made using stage readings taken from permanent elevation <br />marks on the boat ramp. Reconstruction of the boat ramp in 1996 included a survey of <br />new elevation marks. Storage measurements prior to 1996 may be less accurate due to <br />settling of the original boat ramp. <br />Releases from the reservoir into the outlet canal are measured at a 20-foot Parshall flume <br />with a clock measuring device located below the embankment. In addition, there is a 15- <br />footParshall flume with a clock measuring device located approximately 40 miles below <br />the embankment. The District is contemplating installing a third measuring device on the <br />outlet canal approximately 20 miles below the embankment to help identify locations and <br />amount of seepage losses. <br />Irrigated Acreage and Crop Types: The North Sterling Irrigation District encompasses <br />40,916.64 irrigable acres, with approximately 34,500 acres (84%) currently irrigated. <br />The District is surveying farmers within the system and preliminary results of the survey <br />indicate the following crops: <br />• alfalfa (55%) <br />• corn (25%) <br />• sugar beets (10%) <br />• wheat, beans and hay grasses (10%) <br />Historically more lands in the District were used to raise sugar beets. <br />Reservoir Seepage/Evaporation Information: No studies have been conducted to quantify <br />seepage losses from North Sterling Reservoir. Reservoir seepage generally accrues to <br />lands directly below the reservoir and directly to the South Platte River. Seepage water is <br />not collected and conveyed in a controlled channel. Evaporation losses from the reservoir <br />are estimated to be approximately 4 feet per year. Evaporation is not measured at the <br />site. <br />HydroBase Data: Storage records are available in Hydrobase under the North Sterling Reservoir <br />structure and under the Point of Rocks Reservoir (ID 6403551) structure. The District <br />provided paper records of storage contents for the period 1930 through 2003, which are <br />graphed in Figure 2 for the study period. In addition, the District maintains records of <br />releases that are available over the period 1930 through 2002. According to the District's <br />records, historical releases into the outlet canal average over the past 20 years 82,256 <br />acre-feet per year. <br />North Sterling Irrigation District.doc Page 7 of 11 <br />